public void Test_S2CellUnion_FromBeginEnd()
{
// Since FromMinMax() is implemented in terms of FromBeginEnd(), we
// focus on test cases that generate an empty range.
S2CellId initial_id = S2CellId.FromFace(3);
// Test an empty range before the minimum S2CellId.
S2CellUnion cell_union = new(new List <S2CellId> {
initial_id
});
S2CellId id_begin = S2CellId.Begin(S2.kMaxCellLevel);
cell_union.InitFromBeginEnd(id_begin, id_begin);
Assert.True(cell_union.IsEmpty());
// Test an empty range after the maximum S2CellId.
cell_union = new S2CellUnion(new List <S2CellId> {
initial_id
});
S2CellId id_end = S2CellId.End(S2.kMaxCellLevel);
cell_union.InitFromBeginEnd(id_end, id_end);
Assert.True(cell_union.IsEmpty());
// Test the full sphere.
cell_union = S2CellUnion.FromBeginEnd(id_begin, id_end);
Assert.Equal(6, cell_union.Size());
foreach (S2CellId id in cell_union)
{
Assert.True(id.IsFace());
}
}
